1. Field of the Invention
The present invention relates to a silicone compound, photocurable liquid ink using the silicone compound, and a method of manufacturing the ink.
2. Description of the Background Art
Printers using blocks have generally been used to print images having a relatively long run length such as local advertisement, materials prepared for meeting, etc. in office, and large posters. In recent years, instead of such typical printers, on-demand printers that respond to diversified needs quickly and reduce the stock have begun to gain acceptance. Electrophotographic image forming apparatuses using dry toner and liquid toner and ink jet printers capable of producing quality images at high speeds have been expected as such on-demand printers.
On-demand printers are known to use solvent ink or solvent liquid toner containing pigments and organic solvents as the printers using blocks. However, in this technology, such organic solvents evaporate in an amount to an impermissible level when used to print images with a significant run length. This causes an atmosphere contamination problem by vaporized organic solvents. Therefore, it is necessary to provide a facility for waste of the organic solvents and/or a mechanism to retrieve the solvents.
In inkjet printers, the solvent ink can be used in a close system until the ink is discharged to a printed surface. Therefore, the atmosphere contamination problem is more or less relieved by taking a suitable measure for wasting.
However, different from the ink for use in printers using blocks, the ink for use in inkjet printers is required to have suitable fluidity for discharging ink. Therefore, with regard to the technology described above, it is necessary to increase the solvent density in the ink. The problem of atmosphere contamination ascribable to the organic solvents is inherently unsolved.
In addition, when solvent ink is used, the image quality is affected by the printing surface. For example, a permeable printing surface tends to blur but an impermeable printing surface makes it difficult to fix images. Furthermore, it takes some time before the ink layer formed on the printing surface becomes dried. Therefore, when a thick image is formed in a large printing surface, blurred images are easily produced due to the fluidity. That is, it is not easy to produce quality images with this technology.
The problem of atmosphere contamination ascribable to organic solvents for the inkjet printer still remains with regard to the liquid toner.
As a solution to this problem, using coloring particulates dispersed in a non-volatile liquid such as silicone oil is known. However, in such liquid toner, bonding of coloring resin particulates tends to be inhibited by the presence of non-volatile liquid when fixing images on a recording medium. Therefore, it is necessary to remove insulating liquid (carrier liquid) in the liquid toner using multiple removing rollers before image fixing, which complicates an image forming apparatus using the liquid toner. This is disadvantageous to demand for high speed performance.
As technologies to the problems described above, using a photosensitive ink and a printer system have begun to be appealing. This technology is to quickly optically-cure photosensitive ink discharged on printing surfaces. The photosensitive ink contains polymerizable monomers or oligomers, photopolymerization initiators, and pigments and is capable of producing images quickly by curing the ink by polymerization reaction upon application of light such as ultraviolet.
Furthermore, according to this technology, since the ink layer can be non-fluidized upon application of light, relatively high quality images can be produced. For example, as the liquid ink for use for inkjet, Japanese Patent Application Publication No. 2008-24881 (JP-2008-24881-A) describes curable compositions that contain ethylene-based unsaturated compounds such as (meth)acrylates and polystyrenes as ethylene-based unsaturated compounds having particular structures.
In addition, Japanese Patent No. 3985459 (JP-3985459-B) describes active energy line curable inkjet ink containing a compound having two or more acrylate bondings which contain two or more ethylene-based double bonding and 2-phenoxy ethylacrylate having one ethylene-based double bonding. However, although (meth)acrylates having a relatively low molecular weight for use in the ink satisfy the basic properties such as viscosity and optical curing speed, they have problems with regard to handling properties such as odor and skin sensitization. Having a good combination of the basic properties of optical curing and handling properties is difficult.
Furthermore, as the liquid ink for electrophotography, JP-3442406-B describes curable liquid vehicle having a particular viscosity range and a particular resistance range such as (meth)acrylic-modified silicones.
To be specific, the silicone portion is described to have an aliphatic or aromatic siloxane chain or ring having a particular dimethylsiloxane unit.
In addition, JP-4150118-B describes containing reactive silicone compounds in molecules. The reactive silicone compounds have functional groups such as isocyanates group, Si—H group, vinyl group, amino group, hydroxyl group, epoxy group, and methacylic group in molecules and in particular the silicone compounds having methacrylic groups are described in Examples.
However, since (meth)acrylic compounds for use in such ink have silicone portions in the molecules, the concentration of the reactive portion decreases (the number of collisions decreases) so that the optical curing speed is insufficient. Therefore, it is difficult to meet the demand about high speed performance